A class of wireless services intended for quick, efficient, one-to-one or one-to-many (group) communication has existed in various forms for many years. In general, these services have been half-duplex, where a user presses a “push-to-talk” (PIT) button on a phone/radio to initiate a group communication. If granted the floor, the talker then generally speaks for a few seconds. After the talker releases the PTT button, other users who are available may request the floor. These services have traditionally been used in applications where one person needs to communicate with a group of people, such as field service personnel or taxi drivers, generally known as group communication services.
There is a need, therefore, for mechanisms that allow a user or a group of users to efficiently detect or announce information, such as user presence and/or location information, to other user or group of users.